Control apparatus for radio receivers



Oct. 12, 1948. L. l.. ROYAL 2,450,918

CONTROL APPARATUS FOR RADIO RECEIVERS Filed April '6, 1946 2 Sheets-Sheet l FIG.

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INVENTOR.

ROYAL ATTORNEYS Oct.v l2, 1948. L.. L. ROYAL CONTROL APPARATUS FOR RADIO RECEIVEHS 2 sheets-sheet 2 Filed April 6. 1946 FIG. 4

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INVENTOR. LESLIE L. ROYAL BY MM 4m ATTORNEYS Paiented Oct. 12, 1948 UNITED STATES TNT QFFICE Leslie L. Royal, Chicago, Ill., assignor to'elmont Radio Corporation, Chicago, Ill., a corporation oi' Illinois Application April 6, 1946, Serial No. 660,027

Claims.

The present invention relates to control apparatus for radio receivers and more particularly to manually operable automatic tuners of the mechanical type for such receivers. The present invention is concerned with an improvement on U. S. Letters Patent Nos. 2,130,153, 2,154,406 and 2,172,288, and specically is an improvement on copending Marholz application Serial No. 660,028 led concurrently with the present application and assigned to the same assignee as the present application.

Various push button actuated mechanical control devices are commercially available for selectively controlling the tuning elements of radio receivers. In general, such mechanical control devices or automatic tuners comprise.l a series ofv manually actuated push buttons which enable the listener to selectively tune in particular stations merely by pushing or actuating the push buttons. In addition, the receiver usually includes manual means for tuning the receiver to any other broadcasting station within the range of the receiver in addition to those for which the automatic tuning arrangement including the push buttons is set. In one form of automatic tuner for radio receivers a series of variably positioned cams are provided along the shaft, one for each of the push buttons. Suitable means are provided for holding these cams in predetermined positions relative to the tuning shaft so that when a push button is actuated, its associated cam is rotated, with the consequent rotation of the tuning shaft to a predetermined position corresponding to the particular station setting for which the push button and associated cam have been adjusted. In order initially to set the automatic tuning arrangement or to change the setting thereof, it is necessary to produce relative movement between the cam and the tuning shaft after which the cam is locked to the shaft in a predetermined position relative thereto.

In the tuning arrangement disclosed in the above-mentioned patents the cams -or control members are positioned along the tuning shaft in between frictional ,means and suitable spacing sleeves are provided between the frictional means associated with adjacent cams or control means. The cams are locked to the shaft by applying a compressive force to the end of the stack of cams,

frictional means, and spacers arranged on the tuning shaft, and generally referred to as the cam stack, whereupon each cam is frictionally heid between its frictional means generally comprising a pair of washers one on either side of the cam which are mounted on the shaft in such a (Cl. 'i4-10) manner that relative rotation with respect to the shaft is prevented. A suitable manually operable tuning knob on the end of the tuning shaft for rotating the same is commonly employed. In order to apply a compressive force to the cam stack it was common practice to provide a screw extending through the tuning knob. This screw was operable by means of a screw driver applied thereto from the front of the tuning knob. Although this arrangement has been found to be very satisfactory the screw for adjusting the pressure on the cam stack and extending through the tuning knob was formed of conducting material electrically connected to the tuning shaft so that it was possible for a high potential to exist at the front of the tuning knob in the event that some defect occurred in the radio set. Even when such a screw was recessed within the tuning knob there was still the possibility of shock, thus making it difiicult to obtain the approval of the Underwriters Laboratories. Accordingly it would ,be desirable to eliminate the screw extending through the tuning knob for adjusting the pressure on the cam stack while retaining its function and still providing a simple, inexpensive construction.

It is yan object of the present invention, therefore, to provide a new and improved automatic tuning arrangement which overcomes the diiiiculty enumerated above.

it is another object of the present invention to provide an automatic tuning device of the type mentioned above in which the possibility of obtaining an electrical shock through manipulation of the tuning knob is completely eliminated.

It is a further object of the present invention to provide a new and improved automatic tuning mechanism which can be set and reset merely by vmanipulation of the manually rotatabletuning knob without the requirement of eXtra tools or equipment. f

A still further object of the present invention is to provide a new and improved manually operable automatic tuner for radio receivers having a plurality of control elements on a rotary shaft with the control elements adapted to be simultaneously locked tothe control shaft solely by manipulation of a tuning knob.

Further objects and advantages of the present invention will become apparent as the following description proceeds and the features of novelty which characterize the present invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of the present lnvention reference may behad to the accompanying drawings in which:

Fig. 1 is a perspective view of a radio receiving set embodying the present invention;

Fig. 2 is an enlarged perspective and somewhat schematic View partly in section f the tuning mechanism of the present invention employed in the receiving set of Fig. 1;

Fig. 3 is a sectional view of the tuning knob and a portion of the cam stack yof Figs. 1 and 2 with the cams in the locked condition;

Fig. 4 is a sec-tional View similar to Fig. 3 showing the tuning knob and a portion of the cam stack with the cams in the unlocked ycondition to permit relative movement between the control members or cams and the tuning shaft;

Fig. 5 is a sectional view taken yon line 5-5 of Fig. 3;

Fig. 6 is a sectional View `of a portion vof the device shown in Fig. 3 taken on line B-G of Fig. 5; and

Fig. 1 is 'a View similar to Fig. 6 showing a modified construction.

Although the present invention is ladaptable for use with any apparatus employing tuning mechanisms such as radio receivers or radio transmitters, it is especially adaptable for use with radio receivers employing a relatively small plurality of push buttons I3 mentioned above,

cabinet often referred to as a midget receiver and the invention has been specifically illustrated in connection with such an applicati-on.

Referring now to the drawings there is illustrated in Fig. 1 a radio receiver generally indicated at ID, comprising a cabinet II of any conventional style. provided for manually tuning the receiving set l0 and in addition a plurality of push buttons I3 are also provided which may be used to tune in certain specic stations to which the set is frequently tuned.

The tuning mechanism for the radio receiving set ID of Fig. 1 comprises a rotary tuning shaft I4 which is suitably journalled in frame members I5 and I6 supported from a base member I1. The rotary shaft i4 which is provided with a longitudinally extending key way I8, fbest shown in Figs. 2, 3 and 4 of the drawings, is coupled or otherwise suitably connected to a resonance frequency changing means or a frequency control device for tuning the radio receiver to parti-cular stations. This resonant frequency changing means may comprise a variable inductan-ce or variable condenser and has been illustrated in Fig. 2 of the drawings as comprising a variable condenser I9 having a plurality of rotor plates 2l] fixedly mounted for movement with rotation of the shaft I4 and a plurality of ycooperating stator plates 2|. The rotor portion of the condenser l9 is preferably rotatable through an angle of substantially 180. Rotation of the tuning shaft I4 will cause the capacitance of the variable condenser I9 to vary with the resultant tuning of the radio receiving set I!) to any desired station within the range of the receiver. The tuning knob I2 mentioned above is associated with the shaft lli at the end remote from the condenser I9 in a manner which will be described in greater detail hereinafter. In any event, rotation of the knob I2 causes rotation of the shaft I4.

In accord-ance with the now well-known automatic mechanical tuning mechanisms for radio receivers such as are disclosed in the above-mentioned patents, the s-haft Ill is also controllable insofar as rotation thereof is concerned by the A suitable tuning knob i2 is whereby particular stations to which the listener frequently desires to listen may be tuned in merely by actuating one of the push buttons which automatically causes the desired rotation to be imparted to the shaft I4 without further effort than to actuate `one of the push buttons.

It should be understood that each push button I3 may be 'associated with a selector unit comprising ya slidable member which is moved in a generally longitudinal direction upon actuation of the push butt-on 13. As illustrated in the drawings, however, each of the push buttons I3 only one of which is shown in Fig. 2 thereof, is associated with an L-shaped lever or rnember 22 having a notched-out portion 23 adapted to be slipped over and pivotally Imounted on a support or shaft 24' supported between the frame members I5 and I6. As was mentioned above, in lorder to simplify the disclosure only one such push button and L-shaped member is shown in Fig. 2 of the drawings but it will be understood that a series of such levers or members 22 will be provided along the support 24 which may be spaced in any desired manner such as by suitable spacing sleeves 25. The portions of the shaft Ill and the support 22 which lhave 'been omitted from 2 of the drawings are shown in dotted lines and the associated push buttons and other members have been completely omitted.

In order to hold the L-shaped lever 22 in position for pivotal movement relative to the support E@ Ithere is provided a spring member 26 which is '0f one-piece hairpin-like construction comprising a hooked end 2Ea which extends over the top edge of L-shaped lever 22 with a bowed retaining portion 26b passing beneath the support 24 and extending to ya looped portion 26e hooked over the top edge of the L-shaped lever 22 to the rear of the support 24. The spring 26 is also provided with an extension d which engages the base I1 of the chassis to maintain the L- shaped lever 22 in the position indicated in Fig. 2 of the drawings except when a force is applied to the push button portion I3. The end of the L-shaped lever 22 remote from push button i3 is provided with a roller 21 pivotally `attached thereto by means of a pin or stud 28. If desired this roller 21 may be dispensed with and instead the end of the L-shaped lever 22 may be lmerely a rounded projection or the like.

In order that different desired station settings may be imparted to the tuning shaft Il by means of push buttons i3, the selector units comprising the series of L-shaped levers 22 only one of which is shown in Fig. 2 of the drawing, are each adapted to engage the edges of cooperating selecting or control members comprising heart-shaped cams 29. Each heart-shaped cam 29 is provided with an opening for accommodating the tuning shaft Ill and is normally held in a fixed relative position therewith which position may be varied by means to be described hereinafter. Also, cam 29 is positioned on the shaft I4 so as to be engageable by the roller 21 of its associated L-shaped lever 22. Furthermore each of the cams 29 is positioned between a pair of washers 30 and SI, at least one of which is provided with a cooperating extension 32 for sliding in the key way I8 whereby at least one of the washers 3i! or 3| is non-rotatably positioned on the shaft I4. Preferably the washers 32 and 3l are identical and comprise a pair of shoulders 33 engageable with a stop lug Bil illustrated as a punched-out portion of heart-shaped cam 29. This stop lug 34 of frame member l5.

Yis provided on'only one side of cam 29 and serves to'limit the relative movement of cam 29 and shaft I4 to substantially 180 degrees. It will be understood that the shoulders 33 need not be provided on the washer 3l since no stop lug is provided on that side of cam 29. However, in order to keep the numberof different parts of the apparatus at a minimum it is preferable to employ identical washers and 3l on either side of the cam 29, which washers provide the frictional means for locking or holding the cam 2S in a fixed position relative to the shaft I4.

In order that the cams 29 may be held in spaced relationship along shaft I4 suitable spacing means or sleeves are provided between the washer 34 of one cam and the washer SI of the adjacent cam. In addition, shaft I4 is provided with a stop member 36 near the end thereof adjacent the variable condenser I9. The spacing means 35,

the washers 3l! and 3E and the cams 2S are as- L sembled on the shaft I4 from the end remote from stop 35. All of these members are rotatable about shaft I4 except the washers 39 and 3l which are keyed against rotation by the portions 32 thereof. However, all of these members are longitudinally movable or slidable on shaft i4 and this stack of members generally referred to as the cam stack may lbe compressed against stop member 36 whereby the frictional means coinprising washers 30 and 3l will firmly hold the asl sociated cam 29 in a fixed non-rotatable position relative to shaft I4.

In order to control the frictional means by compressing or releasing the cam stack `comprising the cams, washers and spacing sleeves, there is :2

provided adjacent the end of tuning shaft I4, remote from stop member 3E, as is best shown in Fig. 3 of the drawings, a spring washer 3l, a washer 38, and a bushing 39 which has a portion of reduced cross-section adapted to fit into an opening 46 in the frame member I6. The members 3l, 38 and 39 are mounted on the cam side In accordance with the present invention there is provided on the knob side of the frame member I6 and coaxially positioned relative to the tuning shaft I4 a bevelled or tapered washer 4I which cooperates with a collet 42, best shown in Figs. 3, 5 and 6 of the drawings.k Collet 42 is provided with a cylindrical portion 42a, having an internally threaded bore 42h for threaded engagement with a threaded portion of reduced cross section Illa at the end of the tuning shaft I4. Collet 42 is provided with a plurality of lingers 42C formed of spring mate rial whereby the fingers tend to spread apart in the manner best shown in Fig. 4 of the drawings. The free ends of the fingers remote from the cylindrical portion 42a of collet 42 are provided with flared end portions 42d having the necessary curvature for engaging with the bevelled surface 4Ia of the washer 4l. The collet 42 is threaded on the end I4a of tuning shaft I4 with the spring tensioned fingers 42e extending in a direction toward the cam stack. Preferably the collet 42 is threaded on the end of the shaft I4 in a manner to provide the desired initial friction so that the cams 29 are rotatable relative to shaft I4 but are held by frictional means comprising washers 3G and 3| so as to remain in a predetermined position when moved thereto. It is obvious that by changing the position of the collet 42 relative to shaft I4 this tension can be varied in any desired manner. YThe initial adjustment for the tension is shown in Fig. 4 and the spring washer 31 also furnishes a predetermined amount oftensionto hold cams 29 in a predetermined position on shaft I4, which position, however, may be changed by applying a rotatable force thereto since the frictional means are in the re4 leased position. Preferably the end Illa of shaft i4 and the bore 42h of collet 42 are provided with a micrometer thread whereby the desired initial frictional adjustment may readily be obtained.

Once the desired adjustment of initial pressure against the .bevelled washer 4i is obtained suitable means for tightly locking the cams 29 against rotation relative to the shaft I4 are required. In accordance with the present invention this means comprises tuning knob l2 preferably formed of insulating material such as plastic or the like and having a hollow shank portion IZa which extends through an opening I Ia in cabinet I i. `A metal shank or bushing 43 of tubular form and having a length substantially equal to the overall length of collet 42 is molded or otherwise suitably fastened in the bore 44 in the shank IZa. The end of the bore 44 specifically designated by the numeral 45 forms a stop so that when the metal shank 43 is slipped over the collet 42 the axial movement of the tuning knob l2 in a direction toward the bevelled washer 4I is determined by engagement of the portion 42a of the collet 42 with the stop 45. In order that the end 'of tuning shaft Illa may not interfere with stop 45 shank I2a is preferably provided with a bore 4t for receiving the end I4a of shaft i4 whereby the stop 45 is free to determine the maximum axial movement of the knob l2 in a direction toward the b-evelled washer 4I, The inner diameter of the metal shank or bushing 43 is such that when it is vslipped over the collet 42 the ared end portions 42d of the fingers 42e are compressed so es to cause movement of bevelled washer 4I to the left as viewed in Figs. 3 and 4 of the drawings, thereby compressing the cam 4stack and firmly locking cams 29 between the washers 3E? and 3i comprising the frictional locking means. The unlocked position of the cam stack is clearly indicated in Fig. 4 of the drawings while the locked position is indicated in Figs. 2, 3 and 5.

In order that the tuning knob i2 with its integral metal shank or bushing 43 cannot be completely removed from tuning shaft I4 so that tampering with the initial adjustment of the collet 42 can take place, there is preferably pro vided. a spring locking clip 49 best shownin Fig. 5 of the drawings, which has a prong 4ta extensible through an opening 42a in the metalI shank or bushing 43. Actually the prong 4ta extends between the spring tensioned lingers 42o of collet 42 and into the key way I8 of the shaft I 4.

This prong 49a of spring clip 49 engages with the cylindrical portion 42a of collet 42 to limit the maximum outward movement of knob l2 relative to cabinet l l which is shown in Fig. 4.. The spring clip 49 is positioned within the cabinet l I so that it is necessary to remove this clip before the tuning knob l2 can be removed from the end of the shaft I4. In this way the radio listener is prevented from tampering with the initial adjustment furnished the collet 42 Without first removing the spring clip 49. It is obvious that the spring clip 49 cannot be inserted for assembly until the tuning Yknob Il is lined up so that the opening 43a, in the shank 43 registerswith the key way I3 and furthermore registers with the space between two adjacent spring fingers 42o of collet 42. In addition the opening 43a in the shank or bushing 43 must have been moved inwardly far enough to clear the solid cylindrical portion 42a of the collet 42. It should be obvious that the spring 49 performs no function insofar as control of the frictional means is concerned but is provided to prevent inadvertent removal of knob I2 and limit the axial movement thereof to that required for unlocking the frictional means to permit adjustment of cams 29. It, however, also functions to key the tuning knob I2 to the tuning shaft I4 having key way I8.

fn Fig. 7 there is illustrated a modification of the collet 42 generally indicated at 42', The only difference between collet 42 and collet 42 is that the solid portion 42a of Fig. 6 designated as 42'@ in Fig. 'l is provided with cuts 42e having a tapered bottom which cuts register with the space between spring tensioned fingers 42o. When employing the collet 42' in the arrangement disclosed in Figs. 3 and 4 of the drawings the spring clip 49 must be completely removed from the shank 43 for disassembly just as in connection with the arrangement described above. However, during the assembly operation spring clip 49 may be placed on shank 43 with the prong 49a extending through the opening 43a. When the knob I2 is slipped into position prong 49a. will ride :through one of the cuts 42e over the tapered bottom thereof, thus somewhat simplifying the original assembly operation since it is considerably easier to apply the spring clip 49 to the shank 43 prior to placing the knob I2 in position relative to the tuning shaft I4 than it is after the knob I2 is in the position indicated in Fig. 4 of the drawings, for example.

The operation of the tuning mechanism de' scribed thus far will be obvious in View of the detailed description included above. Assuming that the members defining the cam stack are in position on the tuning shaft I4 and the knob I2 is removed from the end of the shaft I4 the collet 42 is first adjustably positioned on the shaft I4 to provide the desired initial friction by compressing the cam stack a predetermined amount. It is desirable that this initial friction be such that the cams 29, although rotatable relative to the shaft I9 when a small force is applied thereto by means of L-shaped levers 22 will, without such force, remain in a fixed position relative to the shaft I4. The tuning knob I2 is now moved into the position indicated in Fig. 4 of the draW- i' ings with the shank 43 slipped over a portion of collet 42. The spring clip 49 can then be placed in position with the prong 49a extending through the opening 43a which must be in registry with the key way I8 and the space between two adjacent spring fingers 42e of the collet 42. With the parts positioned as indicated in Fig. 4 the tuning knob I2 is rotated so as to tune in a par-- ticular broadcasting station. Then one of the push buttons I3 is actuated so that the associated roller 2'! engages with the edge of its cooperating cam 29 rotating this cam 29 relative to the shaft I4 until the roller 21 moves into engagement with the low point of the cam 29 whereupon the cam 29 has assumed a predetermined position relative to the shaft I4 which corresponds to the particular station to which the receiver is tuned. The associated push button I3 is then released and the tuning knob I2 is rotated to another station whereby another cam 29 on the shaft I4 may be moved in the manner described above to a predetermined position difiering from the position of the first cam under consideration. This process is repeated until all of the cams 29 on the tuning shaft I4 have been moved to a different predetermined position relative to the shaft I4. The cams 29 are then locked in a fixed position on the shaft I4 merely by moving the tuning knob I 2 in an axial direction with respect to the shaft 54 from the position shown in Fig. 4 of the drawings to the position shown in Fig. 3. The shank 43 engages the flared ends 42d of spring tensioned fingers 42e of collet 42 and compresses them whereby they slide along the bevelled surface of bevelled washer 4I moving the axially movable members defining the cam stack in a direction toward stop member 36. This compressing force causes the washers 30 and 3| associated with each cam 29 to lock the respective cams in position. All of the cams are locked in position simultaneously with the arrangement described above.

As is obvious from Figs. 3 and 4 of the drawings there is no conducting part of the receiver extending outside of cabinet II so that the possibility of receiving a shock is completely eliminated. Furthermore the adjustment or setting of the cams 29 can be accomplished merely by limited axial movement of the tuningknob I2 without the requirement of additional tools such as screw drivers or the like. In addition the tuning knob I2, which need not be provided with a bore for an adjusting screw, provides a very pleasing appearance. Furthermore with the initial adjustment of the friction of the cam stack made at the factory the spring clip 49 prevents this adjustment from being inadvertently tampered with and assures proper tuning operation. In addition to the above advantages the present invention provides for a very foolproof construction which is simple to assemble and inexpensive to manufacture.

It will be apparent to those skilled in the art that the present invention is not limited to the particular construction shown but various changes and modifications may be made without departing from the spirit and scope thereof, and it is aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the present invention.

I claim:

1. Ein a frequency control device for a radio receiver or transmitter including a movable control element for varying either the inductance or capacitance of a tuning circuit, a selecting member carried on said control element for both fixed and relative movement therewith, frictional means for locking said member and said element in a fixed relative position, and actuating means engageable with said member to move said member and consequently said element as a unit to a position predetermined by the relative position l of said element and said member; means for controlling the condition of said frictional means comprising, manually engageable means independent of said actuating means for moving said control element, a bevelled member movable with respect to said control element for increasing or decreasing the frictional effect of said frictional means, a collet having spring fingers at one end thereof engaging the beveled surface of said member, and means responsive to a predetermined movement of said manually engageable means for causing said collet to move said beveled member to vary the condition of said frictional means.

2. In a control device for a radio receiver including a rotary shaft, a cam mounted on said shaft for relative movement therewith, frictional means for holding said cam in a predetermined fixed position on said shaft, and a selector structure for engaging said cam and causing rotation of said cam and said shaft as a unit; means for controlling the condition of said frictional means comprising, a tuning knob including an extended shank positioned on the end of said shaft for rotating the same, and means including a beveled washer and a collet surrounding said shaft and having spring tensioned fingers engaging said washer for controlling said frictional means, said shank engaging said collet to move the same in response to axial movement of said knob.

3. A selector tuning mechanism for a radio receiver comprising in combination, a rotary tuning shaft, a plurality of spaced control members on said shaft, spacing and friction means inter-- mediate the control members and axially slidable therewith on said shaft, means at one end of said shaft for limiting the axial movement of said spacing and friction means and said control members, a tuning knob including a shank positioned on the other end of said shaft for rotating said tuning shaft, a bevelled washer on said shaft, a collet surrounding said shaft having spring fingers engageable with the bevelled surface of said washer and means responsive to axial movement of said tuning knobrfor causing said fingers to slide along said bevelled surface to compress said spacing and friction means whereby said friction means hold said control members in a fixed position on said shaft.

4. A selector tuning mechanism for a radio receiver comprising in combination, a rotary tuning shaft, a plurality of spaced control members on said shaft, spacing and friction means intermediate the control members and axially slidable therewith on said shaft, means at one end of said shaft for limiting the axial movement of said spacing and friction means and said control members, a bevelled washer on the end of said shaft remotel from said last mentioned means, a collet coaxially positioned onsaid'shaft including spring fingers engageable with the bevelled surface of said washer, and a tuning knob for rotating said shaft mounted for limited axial movement relative to said shaft including a shank portion which for one axial position of said shaft engages said fingers to move them along said bevel-led surface of saidwasher thereby compressing said spacing and friction means on said shaft whereby said friction means lock said control members in a xed position on said shaft.

5. A selector tuning mechanism for a radio receiver comprising in combination, a rotary tuning shaft, a plurality of spaced control members on said shaft, spacing and friction means'intermediate the control members and axially slidable therewith on said shaft, means at one end of said shaft for limiting the axial movement of said spacing and friction means and said control members, a. tuning knob including a shank on the other end of said shaft for rotating said tuning shaft, means responsive to axial movement of said tuning knob for compressing said spacing and friction means to cause said friction means to hold said control members in a xed position on said shaft, and a spring clip removably positioned around said shank and having a prong portion extending through said shank for limiting the axial movement in one-direction of said knob.

6. A selector tuning mechanism for a radio receiver comprising in combination, a rotary tuning shaft, a plurality of spaced control members on said shaft, spacing and friction members intermediate the control members and axially slida- 10 ble therewith on said shaft, means at one end of said shaft for limiting the axial movement of said spacing and friction means and said control members, a bevelled washer on the end of said shaft remote from said last-mentioned means, a

collet threadedly mounted on said other end of said shaft including spring fingers: coaxially arranged relative to said shaft and engageable with the bevelled surface of said washer, means including the threaded mounting of said collet on said shaft for adjusting the initial pressure applied to said axially slidable members by said spring fingers through said bevelled washer, and a tuning knob mounted for limited axial movement relative to said shaft including a shank portion which for one axial position of said shaft causes said fingers to move along said bevelled surface of said washer to compress said spacing and friction members on said shaft whereby said friction members lock said control members in a fixed position on said shaft.

7. A selector tuning mechanism for a radio receiver comprising in combination, a rotary tuning shaft, a plurality of spaced control members on said shaft, spacing and friction members intermediate the control members and axially slidable therewith on said shaft, means at one end of said shaft for limiting the axial movement of said spacing and friction means and said control members, a bevelled washer on the end of said shaft remote from said last-mentioned means, a collet threadedly mounted on said other end of said shaft including spring fingers coaxially arranged relative to said shaft and engageable with the bevelled surface of said washer, means including the threaded mounting of said collet on said shaft for adjusting the initial pressure applied to said axially slidable members by said spring fingers through said bevelled washer, and a spring clip removably positioned on said shank having a prong engaging said collet to limit the axial movement in one direction of said knob.

, 8. A selector tuning mechanism for a radio receiver comprising in combination, ya rotary tuning shaft, a plurality of spaced control members on said shaft, spacing and friction means intermediate the control members and axially slidable therewith on said shaft, means at one end of said shaft for limiting the axial movement of said spacing and friction means and said control members, a bevelled washer on the end of said shaft remote from said last-mentioned means, a collet having a solid portion coaxially positioned on said shaft and fastened thereto including spring fingers extending from said solid portion and engageable with the bevelled surface of said washer, a tuning knob mounted for limited axial movement relative to said shaft including a shank portion which for one axial position of said shaft causes said fingers to move along said bevelled surface of said washer` to compress said spacing and friction means on said shaft whereby said friction means lock said control members in a fixed position on said shaft, and a spring clip removably positioned on said shank having a prong portion extending through an opening in said shank and between an adjacent pair of the spring ngers of said collet for engaging the solid portion of said collet to limit the axial movement in one direction of said knob.

9. A control device for a radio receiver including a cabinet, a tuning shaft mounted for rotation in said cabinet, a cam mounted on said shaft for relative movement therewith, frictional means for holding said cam in a predetermined fixed position on said shaft, a selector structure for engaging said cam and causing rotation of said cam and said shaft as a unit, a tuning knob arranged to be mounted outside said cabinet including a shank extending into said cabinet and positioned on the end of said shaft for rotating the same, means responsive to limited axial movement of said knob relative to said shaft for controlling said frictional means, and a removable spring clip on said shank within said cabinet for limiting the axial movement in one direction of said knob.

10. A control device for a radio receiver including a rotary tuning shaft, a cam mounted on said shaft for relative movement therewith, frictional means for holdingT said cam in a predetermined fixed position on said shaft, means for engaging said cam to cause rotation of said cam and shaft as a unit, a bevelled washer on said shaft for controlling said frictional means, a collet having a cylindrical portion and a plurality of spring tensioned fingers engaging said beveled washer, threaded means on said shaft and cooperating threaded means on said collet for adjustably positioning said collet on said shaft, a tuning knob having a shank portion for engaging said spring tensioned fingers in one position of said knob to cause said frictional means to hold said cam in said predetermined fixed position on l said shaft, and a spring clip removably positioned on said shank having a prong portion extending through an opening in said shank and between an adjacent pair of said spring fingers for engaging with the cylindrical portion of said collet to limit the axial movement in one direction of said knob,

1l. A control device for a radio receiver including a rotary shaft having a key way therein, a cam mounted on said shaft for relative vmovement therewith, frictional means having a portion cooperating with said key way for holding said cam in a predetermined fixed position on said shaft, a selector structure for engaging said cam and causing rotation of said cam and said shaft as a unit, a tuning knob including an extended shank positioned on the end of said shaft for rotating the same, means including a collet comprising a cylindrical portion surrounding said shaft and having spring tensioned fingers extending from said cylindrical portion engageable by said shank for controlling said frictional means in response to axial movement of said knob, and a spring clip removably positioned on said shank having a prong portion extending through an opening in said shank and between an adjacent pair of said fingers into said key way to limit the axial movement of said knob in one direction by engagement of said prong with said cylindrical portion of said collet.

12. A control device for a radio receiver including a rotary shaft having a key way therein,

a cam mounted on said shaft for relative movement therewith, frictional means having a portion cooperating with said key way for holding said cam in a predetermined fixed position on said shaft, a selector structure for engaging said cam and causing rotation of said cam and said shaft as a unit, a tuning knob including an extended shank positioned on the end of said shaft for rotating the same, means including a collet comprising a cylindrical portion surrounding said shaft and having spring tensioned fingers extending from said cylindrical portion engageable by said shank for controlling said frictional means in response to axial movement of said knob, and a slot in said cylindrical portion registering with the space between said fingers and having a tapered bottom whereby said knob having said clip positioned thereon may be moved into position on said shaft without removing said clip from said shank.

13. In a control device for a radio receiver including a rotary tuning shaft having a key way, a cam mounted on said shaft for relative movement therewith, frictional means cooperating with said key way for holding said cam in a predetermined fixed position on said shaft, and means for engaging said cam to cause rotation of said cam and shaft as a unit; means for controlling the condition of said frictional means comprising, a bevelled washer on said shaft, a collet having a cylindrical portion and a plurality of spring tensioned lingers adapted to engage said member, threaded means on said shaft and cooperating threaded means on said collet for adjustably positioning said collet on said shaft, a tuning knob having a shank portion for engaging said spring tensioned fingers in one position of said knob to cause said frictional means to hold said cam in said predetermined fixed position on said shaft, a spring clip removably positioned on said shank having a prong portion extending through an opening in said shank and between an adjacent pair of said spring fingers into said key way for engaging with the cylindrical portion of said collet to limit the axial movement in one direction of said knob, and a stop member associated with said knob for engaging said collet to limit the axial movement of said knob in the other direction.

14. In a control device for a radio receiver including a rotary tuning shaft, a cam mounted on said shaft for relative movement therewith, frictional means for holding said cam in a predetermined iixed position on said shaft, and means for engaging said cam to cause rotation of said cam and shaft as a unit; means for controlling th'e condition of said frictional means comprising, a bevelled washer on said shaft, a collet having a cylindrical portion and a plurality of spring tensioned fingers adapted to engage said washer, threaded means on said shaft and cooperating threaded means on said collet for adjustably positioning said collet on said shaft, a tuning knob having a shank portion for engaging said spring tensioned fingers in one position of said knob to cause said frictional means to hold said cam in said predetermined fixed position on said shaft, a spring clip removably positioned on said shank having a prong portion extending through an opening in said shank and between an adjacent pair of said spring fingers for engaging with the cylindrical portion of said collet to limit the axial movement in one direction of said knob, and means on said collet for permitting said knob to be applied to said shaft with said spring clip positioned on said shank while preventing removal of said knob from said shaft without removal of said spring clip from said shank.

15. A control device for a radio receiver including a cabinet, a tuning shaft mounted for rotation in said cabinet, a cam mounted on said shaft for relative movement therewith, frictional means for holding said cam in a predetermined fixed position on said shaft, a selector structure for engaging said cam and causing rotation of said cam and said shaft as a unit, a tuning knob arranged to be mounted outside said cabinet including a shank extending into said cabinet and 14 positioned on the end of said shaft for rotating REFERENCES CITED the same, means responsive to limited axial movement of said knob relative to said shaft for conlrghf fligvggtgeferens are of record m the trolling saidv friotional means, and a removable spring clip positioned on said shank Within said 5 UNITED STATES PATENTS cabinet and having a prong portion extending Number Name Date through an aperture in said shank for limiting 2,200,211 Benton May 7 1940 the axial movement in one direction of said knob. 2,243,487 Plensler May 27, 1941 LESLIE L. ROYAL. 

